wonderfull blend of simplicity and complexity. extremely intuitive to use, yet very powerfull. i also love how there are no rules, just relaxed guidelines, like "ya wanna play quartertonal piano in 15/16 7tuplets? sure, why not, just write it down"
i'd love to see it developed a bit more (right now it seems there is no way to assign a velocity, and also no way to do repeats). but dayumn its a briliant idea for an app.
also it'd be awesome if there was an option to write on a moving sheet as it plays... and maybe a pressure of a pencil can be used as velocity automation? holy god damn, it's a future of a DAW, i tell ya.
external midi controller support (e.g. seaboard) would be really heplful also. maybe i want too much, but to me it looks like the app has huge potential, but a bit half-baked and too cheap tbh. (maybe a pro pro version for $50 is in order?)